C-Peptide
Results
A C-peptide test measures the level of this peptide in the body.
Normal
Normal values vary from lab to lab. The level of C-peptide in the blood must be read with the results of a blood glucose test. Both these tests will be done at the same time.
C-peptide Fasting: 0.26–0.62 nanomoles per litre (nmol/L) or 0.78–1.89 nanograms per millilitre (ng/mL)
High values
- High levels of both C-peptide and blood glucose are found in people with type 2 diabetes or insulin resistance (such as from Cushing's syndrome).
- A high level of C-peptide with a low blood glucose level may mean an insulin-producing tumour of the pancreas (insulinoma) is present or that the use of certain medicines such glyburide or glimepiride are causing the high level.
- If C-peptide levels are high after an insulinoma is taken out, it may mean that the tumour has returned or that the tumour has spread to other parts of the body (metastasized).
Low values
- Low levels of both C-peptide and blood glucose are found in liver disease, a severe infection, Addison's disease, or insulin therapy.
- A low level of C-peptide with a high blood glucose level is found in people with type 1 diabetes.
- Removal of the pancreas (pancreatectomy) causes a C-peptide level so low it cannot be measured. The blood glucose level will be high.
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| Author: | Jan Nissl, RN, BS Sydney Youngerman-Cole, RN, BSN, RNC | Last Updated: November 30, 2006 |
| Medical Review: | Caroline S. Rhoads, MD - Internal Medicine Hanan Bassyouni, MD - Endocrinology and Metabolism Alan C. Dalkin, MD - Endocrinology | |
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| Topic Contents | |
| Test Overview | |
| Why It Is Done | |
| How To Prepare | |
| How It Is Done | |
| How It Feels | |
| Risks | |
 | Results |
| What Affects the Test | |
| What To Think About | |
| References | |
| Credits | |